Effect of Thickness on Fracture Toughness of Al6061-Graphite

Subject Areas : Mechanical Engineering

S Doddamani ¹ , M Kaleemulla ²

1 - Department of Mechanical Engineering, Jain Institute of Technology, Davangere, Karnataka, India
2 - Department of Studies in Mechanical Engineering, U B.D.T. College of Engineering, Karnataka, India

Received: 2019-06-23 Accepted : 2019-08-24 Published : 2019-09-30

Keywords: MMC, fracture toughness, Taguchi analysis, Al6061-graphite, CT Specimens,

Abstract :

This research work presents the study on fracture behavior of Al6061 with graphite particulate composite produced by the stir casting technique. The materials selected for the proposed work is Al6061 and graphite particles. Compact tension (CT) specimens were utilized to determine fracture toughness for different thickness of composite. In the present work, optimizing the parameters of the compact tension specimens is carried out using Taguchi method. Four parameters and two factors are considered to optimize the parameters. Factors considered are material composition and a/W ratio. From the Taguchi analysis, on compact tension specimens, Al6061-9%graphite is the optimized composition and fracture toughness is maximum for a/W ratio = 0.45. All the compact tension specimens of different thickness (B = 4, 5, 7, 10, 12, 15, 18 and 20mm) of a/W=0.45 were tested to find the fracture toughness. From the results, it was observed that the Kq reduces with increment in thickness to width (B/W) proportions and found to stay consistent for B/W≥0.3. This consistent estimation of Kq for B/W≥0.3 prevail the plane strain fracture toughness (KIc) of the composite.

References:

[1] Anderson T.L., 2013, Fracture Mechanics-Fundamentals and Applications, Taylor & Francis Group, New York.
[2] Zhu X-K., Joyce J.A., 2012, Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization, Engineering Fracture Mechanics 85:1-46.
[3] ASM Handbook, 2001, Composites, ASM International.
[4] Kulkarni D.M., 2004, The effect of specimen thickness on the experimental and finite element characterization of CTOD in extra deep drawn steel sheets, Sadhana 29: 365-380.
[5] Kang Yi-L., 2005, Experimental investigations of the effect of thickness on fracture toughness of metallic foils, Materials Science and Engineering A 394: 312-319.
[6] Toshiyuki M., Tomohiro T., 2010, Experimental T33-stress formulation of test specimen thickness effect on fracture toughness in the transition temperature region, Engineering Fracture Mechanics 77: 867-877.
[7] Toshiyuki M., 2013, A failure criterion to explain the test specimen thickness effect on fracture toughness in the transition temperature region, Engineering Fracture Mechanics 104: 184-197.
[8] Toshiyuki M., 2015, Extended investigation of the test specimen thickness (TST) effect on the fracture toughness (Jc) of a material in the ductile-to-brittle transition temperature region as a difference in the crack tip constraint - What is the loss of constraint in the TST effects on Jc?, Engineering Fracture Mechanics 135: 286-294.
[9] Marco P., 2015, An evaluation of size effect in CTOD-SENB fracture Toughness tests, XXIII Italian Group of Fracture Meeting, Procedia Engineering 109: 55-64.
[10] Pandey A. B., 1998, Effects of thickness and precracking on the fracture Toughness of particle-reinforced Al-Alloy composites, Metallurgical and Materials Transactions A 29(4): 1237-1243.
[11] Raviraj M. S., 2016, Experimental investigation of effect of specimen thickness on fracture toughness of Al-TiC composites, Frattura ed Integrità Strutturale 37: 360-368.
[12] Bharath K.N., 2015, Optimization of notch parameter on fracture Toughness of natural fiber reinforced composites using Taguchi method, Journal of Materials Science & Surface Engineering 3(2): 244-248.
[13] Zamani P., Jaamialahmadi A., Shariati M., 2016, Ductile failure and safety optimization of gas pipeline, Journal of Solid Mechanics 8(4): 744-755.
[14] Assimina A., Pelegri A.T., 2003, Optimization of laminate’s fracture Toughness using design of experiments and response surface, Journal of Composite Materials 37(7): 579-596.
[15] Aluminum 6061-T6; 6061-T651 ASM Aerospace Specification Metals, 2015.
[16] Graphite (C)-Classifications, Properties and Applications of Graphite, 2013, CERAM Research Ltd.
[17] Doddamani S., Kaleemulla M., 2017, Experimental investigation on fracture toughness of Al6061–graphite by using circumferential notched tensile specimens, Frattura ed Integrità Strutturale 39: 274-281.
[18] Begum Y., Doddamani S., 2015, Mechanical properties of Aluminium–Graphite particulate composites, International Journal of Engineering Research & Technology (IJERT) 3(17):1-4.
[19] ASTM Standards, 2017, Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials.
[20] Doddamani S., Kaleemulla M., 2017, Fracture toughness investigations of Al6061-Graphite particulate composite using compact specimens, Frattura ed Integrità Strutturale 41: 490-497.